Handheld or otherwise portable analyzers are frequently used in places like scrapyards, dumping grounds, and recycling centers to recognize and sort objects according to the useful materials they contain. As an example, such an analyzer may employ an analysis technique that is based on X-ray emission spectroscopy. Such an analyzer may be referred to as an X-ray analyzer. As another example, such an analyzer may employ an analysis technique that is based on optical emission spectroscopy. Such an analyzer may be referred to as an optical analyzer.
An X-ray analyzer may employ, for example, X-ray fluorescence analysis. Such an analyzer may be referred to as an X-ray fluorescence analyzer, or as an XRF analyzer for short. An XRF analyzer comprises an initial radiation source, which is typically a small X-ray tube. The initial radiation is directed to the object to be examined or sample, where it causes the emission of fluorescent X-rays at the characteristic energies of the constituents of the sample. The XRF analyzer comprises also a detector, which receives fluorescent X-rays and measures their energy spectrum. The relative intensities of characteristic peaks in the measured energy spectrum reveal the element constitution of the sample.
The designer of the analyzer takes all possible precautions to ensure that X-rays generated in the measurement, i.e. the initial radiation and the fluorescent X-rays generated in the sample, will not constitute a hazard to the user. With appropriate structural solutions the designer tries to ensure that incident radiation is only directed towards the sample, and that fluorescent X-rays are only generated in a limited portion of the sample from which they cannot reach the user. A variety of structural and functional solutions may be used in the front end of the XRF analyzer to ensure that the emission of incident radiation is only possible when the analyzer has been pressed against the solid surface of a sample. Known measures include shutter arrangements in the front end window and/or at the exit aperture of the X-ray tube, as well as mechanical and/or optical proximity sensors that only allow the X-ray tube to be energized when the front end is against a sample.
In some cases the use of an additional radiation shield is recommended. Some sample materials are more prone than others to causing backscattering of incident radiation, and some materials encountered in samples give rise to exceptionally high levels of fluorescent X-rays. The use of an additional shield is typically recommended in analyzing materials of low density and/or powdery samples. However, the user may experience the additional radiation shield as bulky and uncomfortable.
An optical analyzer may employ, for example, laser-induced breakdown spectroscopy (LIBS). Such an analyzer may be referred to as a LIBS analyzer. A LIBS analyzer comprises a laser for generation of a high-energy laser pulse. The laser pulse is focused to the object under analysis to form a plasma plume on a surface of the object to cause atomization and excitation on the surface of the object. The excitation causes light emission at wavelength(s) that are characteristic to elements on the surface of the object. The LIBS analyzer further comprises a detector, which is arranged to receive the light emitted from the object to due to the excitation caused by the plasma plume. Since all elements emit light exhibiting wavelength(s) characteristic thereto, the relative intensities of different wavelengths of light reveal the element constitution of the sample. Hence, in context of LIBS analyzer the detector is essentially a light detector, and a detector of similar kind is applied also in context of other analysis techniques that are based on optical emission spectroscopy.
Also unknown radiation hazards may be encountered when using a portable analyzer. Since it is not known what is in there among the objects to be analyzed, little can be said beforehand about the environment of the measurement posing or not posing a hazard to the user. There is a clear need for solutions that could protect the user of the portable analyzer from hazardous aspects that may occur in the environment in which the analyzer is used, such as ionizing radiation originating from the object or sample under analysis or from its surroundings.